ttsgeb Posted May 24, 2020 Report Share Posted May 24, 2020 (edited) This is a copy of portions of my thread over at BitBuilt https://bitbuilt.net/forums/index.php?threads/xboxdvi.3304/ As some of you may know, the original xbox is really lacking in video output modes for the modern era. It is only capable of analog video out, and doesn't even support VGA through that. Early versions of the xbox use a CX25871 as the video encoder, which can take a variety of digital inputs and in turn outputs analog video. https://html.alldatasheet.com/html-pdf/153349/CONEXANT/CX25871/384/1/CX25871.html My suspicion is that the xbox uses the highest quality of these potential inputs, RGB24. If that turns out to be the case, I should be able to use the Texas Instruments TFP410 to turn these signals into DVI https://www.ti.com/product/TFP410 End goal is to have a board with a BOM of under $20 that I can then install in my absurd stack of xboxen. The catch: This is my first circuit design project and my first PCB design project, so I'm starting out way over my head. Wish me luck, I guess. -------------------------------------------------- I've since found that my initial assumptions were incorrect, and I've made it to my second prototype. It still has issues, but I'll find out soon enough if I'm on the right track. -------------------------------------------------- Edited May 24, 2020 by ttsgeb 2 Quote Link to comment Share on other sites More sharing options...
ttsgeb Posted June 10, 2020 Author Report Share Posted June 10, 2020 Been trying to figure out why I couldn't program the Max V, the bent pins weren't helping, so I finally got around to fixing the chip, still didn't work... Caught the idea that maybe there's more to the JTAG interface than just putting pins there, and sure enough I need to put in a 10k pull up resistor on TMK and a 1k pull down resistor on TCK so when I wake up I'm gonna track down my resistor pack and bodge those in. Hopefully I'll be able to program the thing soon, and don't have to replace the Max V a fourth time. Regardless, there's another board revision in my future. One with everything on one side so JLC can assemble it and a couple of LEDs to let me know I'm getting the power I need. Quote Link to comment Share on other sites More sharing options...
Ryzee119 Posted June 11, 2020 Report Share Posted June 11, 2020 Input to the encoder is YCrCb444. Its a DDR pixel bus. You sure the maxV is fast enough ? At 720p or 1080i the pixel clock is 70ish Mhz. The pixel is ~140Mhz. (About 7ns period) At 480p/i its about 24mhz so not too bad. Im working on a digital hdmi conversion slowly but its hit a few snags 1 Quote Link to comment Share on other sites More sharing options...
ttsgeb Posted June 11, 2020 Author Report Share Posted June 11, 2020 I've seen your project since starting and it looks promising. I'm excited I'm not the only person working on this. Thanks for the info on what the protocol is! Unfortunately, this means the TFP410 and Max V combo probably isn't going to suit my needs. That's a huge bummer, but it means I have to learn more about HDMI/DVI, and it means I might be able to build a more versatile converter. I have no clue if the Max V is going to be fast enough, I came into this knowing nothing, but I figured I want to see this happens, so I might as well try my hand at it. Quote Link to comment Share on other sites More sharing options...
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